''Don't go to the pen -- send a friend'' and ''If you can't do the time, just drop a dime.''

As an example, he uses the upcoming bribery trial of former Illinois Governor George Ryan, who two years ago emptied the state's death row due to the number of factually innocent inmates placed there. Warden begins with:

When Scott Fawell testifies for the prosecution at former Illinois Gov. George Ryan's upcoming federal trial, he will do so under what a government informant in another case memorably called ''the influence of freedom.''In exchange for Fawell's testimony, prosecutors have agreed to slash his own prospective prison time by almost half --from 11 years to six years -- and let off his girlfriend and co-conspirator, Alexandra ''Andrea'' Coutretsis, with no prison time. Welcome to the snitch system.

How often is snitch testimony wrong?

The government keeps no statistics on snitches, but I recently reviewed the cases of 98 defendants exonerated after having been sentenced to death during the last quarter of the 20th century. Thirty-nine of those convictions rested to some degree on snitch testimony, showing pretty much what we would expect: that witnesses with incentives to lie are inclined to do just that.

Is there a remedy? Warden writes,

One idea would be to allow prosecutors to continue to give or promise anything under the sun to snitches for information, provided the information is solely for investigative purposes -- that is, to point to other, more reliable evidence that could then be used in court. Keeping snitches off the witness stand would avoid the bribery issue because whatever the prosecution provided in exchange for information would not influence testimony. More important, banning snitches from the courtroom would serve the interests of justice.